Overview
- A meta-analysis published Wednesday in PLOS One pooled 69 cohort studies tracking millions of adults to examine how activity, sitting, and sleep relate to later dementia.
- Regular physical activity was associated with about a 25% lower risk of dementia, while sitting more than eight hours a day was linked to roughly a 27% higher risk.
- Sleep outside the seven to eight hour range was tied to higher risk, about 18% for less than seven hours and 28% for more than eight hours a night.
- A separate Swedish cohort that followed 20,811 people for 19 years found mentally active sedentary time, like reading or puzzles, was linked to lower risk, including a modeled 7% drop when replacing an hour of passive screen time.
- Researchers cautioned that the evidence is observational with wide differences across studies and only three cohorts on prolonged sitting, calling for intervention trials and better tracking with devices.